A music player app is UI agnostic. What is important for a music player app is to play music. :) Xamarin Forms can provide a nice UX, but if you really want to build some very fancy UI, you might consider using Xamarin Android and Xamarin iOS. But if you want to keep a pretty simple UI, Xamarin Forms will help you have a shorter development timeframe. And it would help you more since you are new to Xamarin.
Whatever your decision is, I wish you good luck! :)